The development of internet technology in Indonesia at this time has been increased. The growing number of new networks created in line with the ever-evolving development of information over the internet has demanded a network system with greater bandwidth and better quality of connectivity. Fiber optic technology (optical fiber) is one of the findings that can answer the problem. However, the application of fiber optic network in Indonesia is still quite expensive. This problem which makes fiber optic network is difficult to be developed. In the design of fiber optic networks, the common problem that is often considered is connecting n nodes with the minimum number of cables. The length of the MST connecting the nodes is the length of the required cables. This research will create an optimization model for the problem of Degree Constrained Minimum Spanning Tree on fiber optic network design, where the algorithm to be used is Modified Prim algorithm.